Book excerpt: This book addresses a phenomenon that has been much studied in anthropology, sociology and administrative science - the social structural foundations of coordinated activity and consensus in complexly differentiated communities and organizations. Such foundations are important because social differentiation makes coordination and agreement especially hard to achieve and maintain. Friedkin focuses on the process of social influence, and on how this process, when it is played out in a network of interpersonal influence, may result in interpersonal agreements among actors who are located in different parts of a complexly differentiated organization. This work builds on structural role analysis which provides a description of the pattern of social differentiation in a population. Interpretation of the revealed social structures has long been a problem. The steps for structural analysis that are proposed in this book are addressed to the above problem. To explain the coordination of social positions, the author pursues the development of a structural social psychology that attends to both social structure and process.